Mount Pinatubo in the Philippines erupting on June 12, 1991. A much larger eruption occurred three days later. Photo: U.S. Geological Survey.

According to a study published online in Nature Communications and co-authored by Alan Robock, Department of Environmental Sciences, explosive volcanic eruptions in the tropics can lead to El Niño events with dramatic global impacts on climate.

Damage from volcanic ash at Clark Air Force Base in the Philippines after the June 15, 1991, eruption of Mount Pinatubo. Photo: Richard Hoblitt/U.S. Geological Survey.

Damage from volcanic ash at Clark Air Force Base in the Philippines after the June 15, 1991, eruption of Mount Pinatubo. Photo: Richard Hoblitt/U.S. Geological Survey.These events occur because the eruptions pump millions of tons of sulfur dioxide into the stratosphere, which forma sulfuric acid cloud, reflecting solar radiation and reducing the average global surface temperature.

The study used sophisticated climate model simulations to show that El Niño tends to peak during the year after large volcanic eruptions like the one at Mount Pinatubo in the Philippines in 1991, which was focused on because it was the largest and best-documented tropical eruption in the modern technology period.

“We can’t predict volcanic eruptions, but when the next one happens, we’ll be able to do a much better job predicting the next several seasons, and before Pinatubo we really had no idea,” said Robock, who has a doctorate in meteorology. “All we need is one number – how much sulfur dioxide goes into the stratosphere – and you can measure it with satellites the day after an eruption.”